1. Field of the Invention
The present invention relates to computer-implemented systems and methods for drawing images, and in particular to a computer-aided drafting tool for defining a precision drawing point based on one or more temporary points.
2. Description of the Related Art
Computer aided design (CAD) and other drawing programs allow the preparation and editing of machine drawings, schematic drawings, and artwork. Typically, the user creates these drawings with the use of a library of objects and a number of drawing tools. These drawing tools allow the user to define and edit lines, polygons, ovoids, and other shapes.
One useful feature in such drawing programs is the ability to draw new objects and to define new precision points using alignment lines based upon geometric relationships with existing objects or portions of existing objects. To accomplish this, the user first selects an interesting point on an existing object such as the end point of a line. The selection of the interesting point allows the definition of a set of magnetic alignment lines, each of which is displayed as the user moves the cursor within a snap distance of each candidate alignment line. The user can then select the precision point along the alignment line. xe2x80x9cMagnetic alignment linesxe2x80x9d are lines in a drawing that can be defined from one or more points identified in the drawing. These lines are used to assist the user in defining other lines and objects, but are not part of the drawing itself. Typically, the magnetic alignment lines are not displayed until a cursor approaches within a snap distance of the line. Once that occurs, the magnetic alignment line, which may optionally include a superimposed secondary cursor, appears.
Although the above-described systems allow the user to use interesting points to define alignment lines, they are limited in that they require that the user-selected interesting points be somehow associated with some existing object or geometry like the end point of a line or the center point of a circle. This can require the user to define one or more objects or shapes solely for the purpose of obtaining precision alignment lines to define a precision point. Not only is this a waste of user effort and time, but the user has to remember to delete the objects, or they will remain in the drawing. What is needed is a method for defining a precision drawing point using user-defined temporary interesting points that can be anywhere in the drawing space and unassociated with any existing objects. The present invention satisfies that need.
To address the requirements described above, the present invention discloses a method, apparatus, and article of manufacture for defining a precision drawing point in a drawing space.
The method comprises the steps of accepting a command to specify a temporary interesting point anywhere in a drawing space on a display, and displaying an alignment line when a command is accepted to move a cursor to within a snap distance of one of a set of pre-settable alignment lines extending from the temporary interesting point.
In one embodiment of the present invention, an indicator is displayed to indicate the position of the user-selected temporary interesting points. Candidate positions for the precision point can be defined and annotated as the intersection of alignment lines from two user-defined temporary interesting points, or can be defined and annotated when the cursor is moved within a length snap distance from one of a set of pre-settable distances from the temporary interesting point and extending along the displayed alignment line. The article of manufacture comprises a program storage device tangibly embodying instructions for performing the method steps described above.
The apparatus comprises means for accepting a command specifying a temporary interesting point anywhere in the drawing space, and means for displaying an alignment line when a command is accepted to move the cursor to within a snap distance of one of a set of pre-settable lines extending from the temporary interesting point.